Physiological and morphological responses to water stress in Aegilops biuncialis and Triticum aestivum genotypes with differing tolerance to drought

Abstract

The physiological and morphological responses to water stress induced by polyethylene glycol (PEG) or by withholding water were investigated in Aegilops biuncialis Vis. genotypes differing in the annual rainfall of their habitat (1050, 550 and 225 mm year–1) and in Triticum aestivum L. wheat genotypes differing in drought tolerance. A decrease in the osmotic pressure of the nutrient solution from –0.027 to –1.8 MPa resulted in significant water loss, a low degree of stomatal closure and a decrease in the intercellular CO2 concentration (Ci) in Aegilops genotypes originating from dry habitats, while in wheat genotypes high osmotic stress increased stomatal closure, resulting in a low level of water loss and high Ci. Nevertheless, under saturating light at normal atmospheric CO2 levels, the rate of CO2 assimilation was higher for the Aegilops accessions, under high osmotic stress, than for the wheat genotypes. Moreover, in the wheat genotypes CO2 assimilation exhibited less or no O2 sensitivity. These physiological responses were manifested in changes in the growth rate and biomass production, since Aegilops (Ae550, Ae225) genotypes retained a higher growth rate (especially in the roots), biomass production and yield formation after drought stress than wheat. These results indicate that Aegilops genotypes, originating from a dry habitat have better drought tolerance than wheat, making them good candidates for improving the drought tolerance of wheat through intergeneric crossing.

Methodology Molecular cytogenetic characterization of the Aegilops biuncialis karyotype

“…A. biuncialis genotypes from dry environments generally have a drought tolerance better than that of wheat. These genotypes may be important for improving drought tolerance in wheat via intergenetic crossing (Molnár et al, 2004).…”

The Use of Hydroponics in Abiotic Stress Tolerance Research

“…This can be overcome with careful supplemental oxygenation (Verslues et al, 1998). Reasonably consistent ranking of drought tolerance of wheat genotypes has been achieved using both a PEG treatment in hydroponics and drying of pots of soil (Molnár et al, 2004). We use an alternative method utilising hydroponics to www.intechopen.com study terminal drought responses in wheat and barley.…”

Characterization of a New Wheat-Aegilops biuncialis1Mb(1B) Substitution Line with Good Quality-associated HMW Glutenin Subunit

“…Aegilops biuncialis Vis., a tetraploid U b and M b genome species, is highly resistant to wheat stem and leaf rusts (Damania and Pecetti 1990), barley yellow dwarf luteovirus (Makkouk et al 1994), drought stress (Molnár et al 2004), salt tolerance (Colmer et al 2006) and osmotic stress . And the species also has a high potential for improving the protein content and flour quality of the wheat grain .…”